A long-term objective of this grant has been to examine the role of nitric oxide (NO) and specific isoforms of NO synthase (NOS) in the cerebral circulation. The role of inducible NOS (INOS)-is poorly defined, particularly in relation to endothelial function. Although iNOS is known to be expressed, within cerebral blood vessels during inflammation and pathophysiological conditions, the functional importance of INOS is not well defined. The overall objective of this project is to examine the influence of iNOS on endothelial function in cerebral blood vessels. The role of superoxide and the influence of the CuZn isofom, of superoxide dismustase (CuZn-SOD) on cerebral vascular function during inflammation will also be a focus. INOS deficient mice will be used to test the hypothesis that INOS impairs endothelial function in a model of inflammation (treatment with lipopolysaccharide, LPS). Preliminary data support this hypothesis. To address the specificity of 'NOS deficiency, a complementation experiment will be performed using adenoviral mediated gene transfer to selectively restore expression of INOS in vessels from iNOS deficient mice. LPS increases superoxide within the vessel wall. Although INOS has been suggested to produce superoxide in vitro under special conditions, the importance of superoxide during inflammation or during 1NOS-mediated endothelial dysfunction is not known. Studies are proposed using CuZn-SOD transgenic and CuZn-SOD deficient mice to examine the hypothesis that CuZn-SOD protects cerebral endothelium and vascular function during inflammation and expression of iNOS. Although several isoforms of SOD are expressed within blood vessels, the functional importance of each isoform, under physiological and pathophysiological conditions, is not known. Lastly, studies are proposed to examine the hypothesis that expression of interleukin-lO within the vessel wall limits expression of iNOS, increases in superoxide and vascular dysfunction during inflammation. Thus, modem molecular approaches will be used to define the role of 1NOS in endothelial function in the cerebral circulation in a model of inflammation. In addition, the studies should provide new insight into the role of superoxide and more specifically the CuZn isoform of SOD in cerebral vascular biology as well as mechanisms of vascular dysfunction believed to contribute to carotid artery disease, cerebral vascular dysfunction, and stroke